title: Isoprene synthesis in plants: lessons from a transgenic tobacco model.
abstract: Isoprene is a highly reactive gas, and is emitted in such large quantities from the biosphere that it substantially affects the oxidizing potential of the atmosphere. Relatively little is known about the control of isoprene emission at the molecular level. Using transgenic tobacco lines harbouring a poplar isoprene synthase gene, we examined control of isoprene emission. Isoprene synthase required chloroplastic localization for catalytic activity, and isoprene was produced via the methyl erythritol (MEP) pathway from recently assimilated carbon. Emission patterns in transgenic tobacco plants were remarkably similar to naturally emitting plants under a wide variety of conditions. Emissions correlated with photosynthetic rates in developing and mature leaves, and with the amount of isoprene synthase protein in mature leaves. Isoprene synthase protein levels did not change under short-term increase in heat/light, despite an increase in emissions under these conditions. A robust circadian pattern could be observed in emissions from long-day plants. The data support the idea that substrate supply and changes in enzyme kinetics (rather than changes in isoprene synthase levels or post-translational regulation of activity) are the primary controls on isoprene emission in mature transgenic tobacco leaves.
authors.affiliation: Department of Biological Sciences, Essex University, Colchester, Essex C04 3SQLancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, England, UK.
authors.forename: Claudia E
authors.initials: CE
authors.lastname: Vickers
authors.affiliation: Department of Biological Sciences, Essex University, Colchester, Essex C04 3SQLancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, England, UK.
authors.forename: Malcolm
authors.initials: M
authors.lastname: Possell
authors.affiliation: Department of Biological Sciences, Essex University, Colchester, Essex C04 3SQLancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, England, UK.
authors.forename: Jullada
authors.initials: J
authors.lastname: Laothawornkitkul
authors.affiliation: Department of Biological Sciences, Essex University, Colchester, Essex C04 3SQLancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, England, UK.
authors.forename: Annette C
authors.initials: AC
authors.lastname: Ryan
authors.affiliation: Department of Biological Sciences, Essex University, Colchester, Essex C04 3SQLancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, England, UK.
authors.forename: C Nicholas
authors.initials: CN
authors.lastname: Hewitt
authors.affiliation: Department of Biological Sciences, Essex University, Colchester, Essex C04 3SQLancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, England, UK.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Mullineaux
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000378:metabolism; D055162:Biocatalysis / Q000187:drug effects / Q000528:radiation effects; D015153:Blotting, Western; D002070:Butadienes; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D002457:Cell Extracts; D002736:Chloroplasts / Q000201:enzymology / Q000528:radiation effects; D002940:Circadian Rhythm / Q000187:drug effects / Q000528:radiation effects; D004896:Erythritol / Q000378:metabolism; D005578:Fosfomycin / Q000031:analogs & derivatives / Q000494:pharmacology; D045782:Hemiterpenes / Q000096:biosynthesis*; D007553:Isotope Labeling; D008027:Light; D053858:Metabolic Networks and Pathways / Q000187:drug effects / Q000528:radiation effects; D008954:Models, Biological; D010420:Pentanes; D010788:Photosynthesis / Q000187:drug effects / Q000528:radiation effects; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D010940:Plant Proteins / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000528:radiation effects; D013696:Temperature; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism* / Q000528:radiation effects
chemical_list: D002070:Butadienes; D002457:Cell Extracts; D045782:Hemiterpenes; D010420:Pentanes; D010940:Plant Proteins; C005059:isoprene; D002245:Carbon Dioxide; D005578:Fosfomycin; C024640:fosmidomycin; D002244:Carbon; D019883:Alkyl and Aryl Transferases; C093854:isoprene synthase; D004896:Erythritol